In recent years, in consideration of oil resource depletion and global warming, better vehicle fuel consumption has been increasingly demanded. In particular, a lean-burn vehicle has been desired. A catalyst used in such a lean-burn vehicle is required to have a function to purify nitrogen oxide (NOx) under an excess oxygen atmosphere. However, a conventional three-way catalyst does not sufficiently purify nitrogen oxide because of an influence of the presence of excessive oxygen. Therefore, a catalyst capable of purifying nitrogen oxide in a lean range in which oxygen is excessively present has been required. Conventionally, a so-called lean NOx trap catalyst that traps and purifies nitrogen oxide in the lean range has been proposed (for example, refer to Patent Document 1).